Pulse width modulation (PWM) of signals and PWM signals are used to provide control and communications within and between a variety of electrical devices, systems, and circuits. For example, PWM signals may be used in power supply applications to regulate output voltage or current; in motor control applications to control the speed of a motor; in audio applications for the amplification and processing of audio signals; in communications applications for encoding, transmitting, and decoding data; etc.
PWM signals may be characterized by the modulation of the duty cycle of a periodic signal. For example, a PWM signal may be a periodic square wave voltage signal whose duty cycle (a relationship of the duration of a phenomenon during a given period to the duration of the period) may vary to change the average value of the signal. The duty cycle of a PWM signal may change from cycle to cycle, may change slowly over an extended period, or may be relatively constant, as determined by each particular application. Changes in duty cycle may increase or decrease the duty cycle as long as the duty cycle is greater than zero percent and less than one hundred percent. A PWM signal may also have different shapes. For example, a triangular signal, a saw-tooth signal, a pseudo-sinusoidal signal, and/or the like, could be PWM modulated to carry control, communication or other data.